From 2aeb98f498ce37742b743080fdc6c8cf64053599 Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Tue, 17 Jan 2012 22:04:26 -0500 Subject: [PATCH] NFS: Ensure that mmapped pages remain stable during writeback Ensure that nfs_vm_page_mkwrite() waits for the page writeback to complete before the application is allowed to modify page contents. The main reason for wanting to do this in NFS is to ensure that the server doesn't get confused if we have to resend the RPC request due to a dropped/missed reply. Signed-off-by: Trond Myklebust --- fs/nfs/file.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/nfs/file.c b/fs/nfs/file.c index c43a452f7da2..4fdaaa63cf1c 100644 --- a/fs/nfs/file.c +++ b/fs/nfs/file.c @@ -530,6 +530,8 @@ static int nfs_vm_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf) if (mapping != dentry->d_inode->i_mapping) goto out_unlock; + wait_on_page_writeback(page); + pagelen = nfs_page_length(page); if (pagelen == 0) goto out_unlock;